The ontogeny of acidic digestive tract in larval turbot Scophthalmus maximus based on H+/K+-ATPase and pepsinogen.

Acidic digestion is an important digestive process of marine fish. In fish stomach, two enzymes are involved in the secretion of hydrochloric acid (HCl) and proteomic digestion: H⁺/K⁺-ATPase and pepsinogen. However, the starting of digestive function in fish is still unclear. To reveal the details of acidic digestion of turbot Scophthalmus maximus in early development, a 40 day of turbot larvae culture was conducted. The H⁺/K⁺-ATPase gene from the turbot S. maximus (smH⁺/K⁺-ATPase) was identified and characterized. Based on our previous discription on pepsinogen of turbot S. maximus, we combined pepsinogen and H⁺/K⁺-ATPase and analyzed the mechanism of acidic digestion in turbot. Results show that the spatial and temporal expression profiles of H⁺/K⁺-ATPase agreed with pepsinogen A and C in turbot, indicating a synergetic action between H⁺/K⁺-ATPase and pepsinogen during the acidic digestion process. In addition, the turbot juveniles showed a faster growth after the expressions of H⁺/K⁺-ATPase gene and pepsinogen gene, demonstrating that pepsin had a higher digestive efficiency, for which a compound diet should be provided to the fish from Day 22 onward. This study provided a reference for biology research and aquaculture of turbot and other marine fishes. [ABSTRACT FROM AUTHOR]